Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 310022
Area Forecast Discussion
National Weather Service Blacksburg VA
822 PM EDT MON MAY 30 2016
The remnants of Bonnie will linger along the South Carolina coast
tonight, before slowly working northeast to the North Carolina
coast Tuesday. A cold front arriving from the west Thursday into Friday
will finally boot Bonnie out to sea by the end of the week.
.NEAR TERM /THROUGH TUESDAY/...
As of 640 pm EDT Monday...
Convection across the western portion of the region is making slow
but sure progress southeast into more central portions of the
forecast area. Currently, the activity was clustered in to main
regions, the Mountain Empire region of southwest Virginia, south
into the mountains and foothills of northwest North Carolina. The
region was across parts of Monroe County West Virginia, northeast
into Bath County Virginia. Other than a few isolated, short
lasting showers, eastern parts of the region have been
precipitation free thanks to good subsidence on the northwest side
of the remnants of Bonnie. Short term guidance still offers
solutions of the ongoing precipitation to continue to gradually
make its way southeast into eastern parts of the area as the
evening and overnight progresses. Have made little change in the
forecast other than highlighting in the very near term where
precipitation chances will be highest. Also, have tweaked hourly
temperatures and dew points based upon the latest observations and
expected trends heading through the evening.
As of 140 PM EDT Monday...
Convection remains quite sparse across the region this afternoon
despite moisture given lack of forcing under capping aloft to the
northwest of the Bonnie remnant. However do expect more clusters
to develop over the west as instability continues to increase
along the faint front/shear axis, so keeping in low to mid chance
pops into this evening mainly west of the Blue Ridge. Short term
solutions then attempt to organize shra/tsra into a broken band
upon heading out to the Blue Ridge near sunset, and into eastern
sections prior to midnight before fading. This remains quite iffy
given the wake subsidence region currently out east and timing
after loss of heating. Thus plan to only include some low pops
heading out into the Piedmont this evening with decreasing
coverage mountains. Once any convection ends, expect enough
clearing west to support areas of dense fog espcly valleys, with
perhaps less out east given the more tropical atmosphere under
some lingering clouds overnight. This may be enough to warrant an
advisory across the mountains later so something to watch.
Otherwise expecting another mild overnight given moist dewpoints
with lows mainly 60 to 65 except for a few cooler 50s mountains.
Faint boundary should shift east of the mountains Tuesday as the
remnant tropical low remains stuck near ILM/MYR through the
afternoon. Models again attempt to swing a band or two of deeper
moisture into far eastern sections while keeping a low level
convergence zone out west. This would again support more scattered
nature deeper convection mountains as forecast CAPE values climb
to above 1k J/KG despite only weak forcing aloft. However pwats
remain quite moist so expecting more heavy rain potential as the
continued low level north/ne trajectory under sw flow aloft will
likely keep showers from moving too much. This more in line with
the latest drier 12z ECMWF, so running again with mainly chance
pops, although spots along and just east of the Blue Ridge may
stay dry per lingering subsidence once fog/low clouds burn off.
Kept highs closer to the warmer mos after a mild start with most
in the 80-85 range.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EDT Monday...
Continued sluggish pattern will result in a repeat performance
Tuesday night of that seen tonight with early convection likely
giving way to fog and only isolated pops per latest drier Nam.
Flow over the west should finally start to turn more southerly
later Wednesday afternoon as the Bonnie remnant slides toward the
Outer Banks by Wednesday night and a weak backdoor front slips
toward the region from the north. Guidance also suggests that weak
shortwave energy may eject across the mountains from the west
later in the day with tropical moisture and instability still in
place. This may allow for a bit more widespread scattering of
convection Wednesday afternoon but still not overly impressed.
Therefore bumped up pops a little but still moreso on the side of
the drier Nam/Euro solutions at this point with still some weak
subsidence in place. Again expect any evening convection to fade
by midnight Wednesday night with added fog around overnight.
Upper heights should start to decrease on Thursday with developing
upper troffiness heading southeast toward the region preceded by a
weak surface cold front in the afternoon. This will allow for a
very congested scenario with the Bonnie remnant near HSE, weak
subsidence over the Piedmont, and a pre-frontal convergence zone
working into deep pwats over the west where aided by orographics
and decent instability. However just how far east lift across the
west gets remains uncertain given latest slower trends, but
perhaps enough to include afternoon likely pops far western
sections and higher chances out to the Blue Ridge.
Temps again of the warm/humid flavor with lows mostly 60s and
highs in the low/mid 80s.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 1245 PM EDT Monday...
Gradual lowering of heights will continue into next weekend as
the upper zonal flow starts to break down and eventually gives way
to a more pronounced trough across the region into early next
week. This should be preceded by passing surface cold fronts with
the initial boundary approaching Thursday night and crossing the
area Friday pending timing of a few differing model solutions.
This looks to put the best coverage of convection over the
mountains Thursday evening and then perhaps southern/eastern
sections Friday. However appears decent chances to likely pops in
order across the CWA per a typical slower scenario than guidance
suggests given the lagging mean upper trough well to the
northwest. Initial boundary should be to the south Saturday with a
brief lull in showers possible before the true secondary front
arrives Sunday. This boundary ahead of a rather potent chilly
upper cold pool for early June that will pivot east across the
region by Day7 and likely knock temps back to below normal levels
for early next week. Ahead of the front looks like added bands of
shra/tsra Sunday followed by more post frontal upslope nature
western showers Monday. Otherwise warm and humid temps with highs
at or above normal to prevail into Saturday despite some drying
early in the weekend. This before seeing somewhat cooler and even
drier air especially mountains by Monday as deeper cool advection
arrives with highs mostly in the 70s west to around 80 east.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 810 PM EDT Monday...
Line of showers and thunderstorms was crossing southeast over the
Blue Ridge at the start of the TAF forecast period. Thunderstorms
will move close to or across the KBCB and KROA airports before
01Z/9PM. These showers and thunderstorms may impact KDAN and KLYH
before 04Z/midnight but expect diminishing coverage and intensity.
Dense fog is then likely across the valleys including KLWB/KBCB,
with MVFR to IFR fog out east. Medium to low confidence as to how
extensive IFR fog may be east of the Blue Ridge. Have kept mainly
MVFR with potential at this point. Should see conditions improve
to VFR shortly after sunrise on Tuesday.
Repeat scenario then likely Tuesday afternoon with heating
resulting in bands/clusters of convection over the mountains and
lingering lighter showers with tropical moisture in the east.
Models suggest the most KROA and KBCB are the most likely sites to
have showers or thunderstorms in the afternoon. Lower confidence
that tropical moisture in the east will spread as far inland as
KDAN and KLYH. With the abundant moisture still in place on
Tuesday the storms will still produce heavy rain with MVFR
Similar setup again Tuesday night with more fog around after any
evening convection ends. Appears convection may be more isolated
Wednesday as the area slides in between the next upstream cold
front and the remnants of Bonnie near the coast. Thus more
potential to see more widespread VFR Wednesday with exceptions
over the east and with any pop up storms across the mountains.
Finally an stronger upper trough will kick what is left of Bonnie
out to sea Thursday-Friday. Expect more widespread showers Thursday
afternoon into Friday ahead of a cold front, making for periods
of sub-VFR ceilings and visibilities. Saturday may be VFR behind
this front and before moisture and lowering conditions return by
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